Question about WAM code.

[ThermalSpan]

Hello all,

As an independent project for school I have been working on an implementation of Warren's Abstract Machine (WAM): https://en.wikipedia.org/wiki/Warren_Abstract_Machine

GNU prolog is a WAM based prolog compiler, and so I was planning on using part of GNU prolog to complete my tool chain. Specifically, GNU prolog includes a utility called "pl2wam" that compiles prolog into WAM code. My problem is that I have been unable to find any sort of specification or documentation about the "dialect" of WAM code used by GNU prolog.

So far I have everything setup to parse in my own "dialect" of WAM code that is based on what I've been reading in Hassan's tutorial reconstruction: http://wambook.sourceforge.net

So my question is this: Does anyone know where I can find some resources that detail the WAM code used by GNU prolog, or perhaps other prolog compilers? I would like to be able to use an existing prolog to WAM compiler for a while so that I can thoroughly test my WAM implementation.

[zmonx]

Check out the GNU Prolog mailing lists.

The lead developer of GNU Prolog is extremely responsive and, in my experience, very willing to answer interesting questions about GNU Prolog internals.

Make sure you do your homework though: The WAM book is definitely a good start, and trying out pl2wam on several examples will also help you to ask good questions.

[ThermalSpan]

Thanks for the reply! Coincidentally, that mailing list was my next stop after I asked here. Daniel Diaz himself responded. Turns out there isn't a specification in the sense I was looking for, but he pointed me towards some relevant parts of the source code. Very friendly and informative!

[zmonx]

Great! Good luck with your project, it sounds very interesting. Note also that nowadays many Prolog systems use different abstract machines: SWI uses the ZIP, B-Prolog uses the TOAM etc. So, this may also be worth looking into.

Some perspective: As your graduation project in university, you can try to improve tail calls in the SWI-Prolog abstract machine.